A host of THQ titles are available at special prices this week on Steam. For the 3rd day, all games in the Dawn of War series (original, 2 expansions and Dawn of War II) are available at 50% off their regular price. In addition, the Civ IV Complete pack (includes Civ IV, Warlords and Beyond the Sword expansions, and Civ IV: Colonization) is on sale for $19.99.

Killing Floor is a first-person co-op survival horror, set in and around London after a mad scientist’s “specimens” have broken loose and gone on the rampage. On Oct. 22 Tripwire will release the “Level Up” Free Content pack, and to celebrate Killing Floor will be available for free on Steam from Oct. 22nd through October 25th.

Mytheon is an online micro transaction game that uniquely combines the best elements of action, strategy and RPG game-play with an emphasis on collectability and combat, set within a fantasy universe steeped in mythologies from across the globe.

System Flaw is an action shooter which makes full use of the Nintendo DSi Camera as a process of the gameplay, featuring 100 levels of gameplay that will have users gyrating wildly as they battle enemies that seem to appear out of the real-time environment of the game player.

Set within a near-fictional, historical WWII setting, players take on the role of the OSA agent BJ Blazkowicz as they are thrust into the unknown and unexpected to battle against combat troops, otherworldly forces, and the dark science created by a supernatural Nazi force hell-bent on world domination.

Zombie Tycoon is a humorous game that puts the player at the helm of their very own ravenous zombie horde! Using a mix of fast-paced action and strategic execution, players can amass a terrifying undead army and conquer the entire world!

Now packed with even more popular pricing games than ever (including Golden Road, Safe Crackers, Secret X and many more) plus tons of new and upgraded game graphics and customizable avatars, The Price Is Right 2010 Edition is the closest that fans can come to Contestant's Row, the Big Wheel & the Showcase without actually being on the show.

Just like on the top-rated TV show, the Family Feud 2010 Edition game pits two families against each other in a contest to name the most popular responses to survey-type questions posed to 100 people. The game includes all the familiar and favorite elements of the show such as the scoreboard, face-offs, strikes, stealing and fast money rounds.

Gran Turismo 5 includes more than 1,000 cars, 20+ locations with 70+ track layouts, diverse racing styles including rally, track, karting, NASCAR, and more, deep online community features and online racing, plus Gran Turismo TV, Course Maker and more.

A new report released today by Inside Network's Justin Smith and Serious Business's Charles Hudson concludes that the total United States market size for virtual goods will reach $1 billion in 2009.